Binary Classifier Ordering for Imbalanced Multi-Class Training

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Solution Overview

Problem

Multi-class classification problems are susceptible to bias due to imbalanced training data, making it difficult to build accurate classifiers as the number of classes increases, and existing techniques to address this issue are complex and time-consuming.

Innovation Solution

A multi-class classification system trains a series of binary classifiers in a hierarchy, removing classified data points from the training dataset as they are classified, and automatically determines the order of classifiers to mitigate bias, using techniques like one-vs-all classification and adaptive ordering to improve accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If traditional multi-class classification methods are used, then classification capability is provided, but bias occurs due to imbalanced training data and accuracy decreases as the number of classes increases

Engineering Contradiction:
Improveclassification accuracyVSAvoidhandling of imbalanced multi-class data
Core Design Contradiction:
Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The multi-class classification problem is segmented into multiple binary classification problems. Each binary classifier handles one class at a time, comparing it against all other classes. This segmentation allows each classifier to focus on a specific class, making the training process more effective with imbalanced data and reducing overall bias.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The approach transforms the multi-class classification problem into a series of binary classification problems by adding a dimensional transformation. Instead of directly classifying among multiple classes, the system creates binary decisions for each class, effectively changing the problem dimensionality from multi-class to multiple binary problems.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Measurement precision

If existing techniques are used to address bias in multi-class classification, then some accuracy improvement may be achieved, but the training process becomes complex and time-consuming

Engineering Contradiction:
Improveclassification accuracyVSAvoidtraining process complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The training process is segmented into independent binary classification training tasks. Each binary classifier is trained separately on its corresponding class, which simplifies the overall training complexity compared to training a single multi-class classifier on imbalanced data. This segmentation makes the training process more manageable and less time-consuming.

Inventive Principle:
Principle #1Segmentation

3Measurement precision

If a series of binary classifiers are arranged in different orders, then training results vary, but determining the optimal order increases computational complexity

Engineering Contradiction:
Improvetraining results consistencyVSAvoidclassifier arrangement complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The system dynamically determines the arrangement order of binary classifiers based on the specific characteristics of the training data. Rather than using a fixed or random order, the arrangement is adapted to the data distribution, which helps achieve more consistent training results while avoiding the need to evaluate all possible permutations.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentUS12554981B2Classifier processing using multiple binary classifier stages
Publication Date: 2026.02.17 INTERNATIONAL BUSINESS MACHINE CORPORATION
  • US12554981B2 patent drawing
  • US12554981B2 patent drawing
  • US12554981B2 patent drawing

AI summary

An embodiment generates a training batch of data points from training data for a plurality of classes and builds a multi-class classifier having a series of binary classifiers arranged in a first order. Each of the binary classifiers is associated with a respective class. The embodiment trains the multi-class classifier with the binary classifiers arranged in a first order and, at each binary classifier, the embodiment identifies data points as belonging to the class associated with the respective classifier and updates the training batch to exclude the classified data points. The embodiment then modifies the multi-class classifier by changing the order of classifiers and repeats the training of the multi-class classifier with the series of binary classifiers arranged in a second order. The embodiment then selects a final configuration of the multi-class classifier based at least in part on a comparison of first training results to the second training results.